Riding lawn mower



FIG. 1 is a front view of a riding lawn mower showing our new design;

FIG. 2 is a rear view thereof;

FIG. 3 is a left side view thereof;

FIG. 4 is a top view thereof;

FIG. 5 is a bottom view thereof;

FIG. 6 is an upper left front perspective view thereof; and,

FIG. 7 is an upper right rear perspective view thereof.

The broken lines in the drawings are directed to environment and form no part of the claimed design. 

CLAIM The ornamental design for a riding lawn mower, as shown and described. 